The present invention relates to communications, communications systems and the like, and more particularly to a lunar or planetary communications system for use in relaying communications between the surface of the moon or other celestial body and the Earth.
Communications with an asset, such as a sensor, probe, robotic lander, observatory or similar device, on the surface of a celestial body, such as the moon or planet, at a pole of the celestial body may be limited due to line of sight constraints between the Earth and the lunar or planetary poles. Additionally, communications from within a crater of interest at one of the poles of the moon may be further constrained by the crater walls resulting in no line of sight between the interior of the crater and the Earth. Further, the farside of the moon or other celestial body may always be out of the line of sight to the Earth. Thus, direct communications to an asset on the surface of the moon or other celestial body may be either partially or totally obscured. With respect to the moon, total obscuration from the poles is caused by line of sight limitations, i.e., not being able to view below the horizon. The moon's rotational axis tilt causes the Earth to appear above the horizon for part of the month and below the horizon for the remainder of the month as viewed by an observer on the lunar polar surface. And as noted above, within a crater the crater walls may totally obscure line of sight even during the most favorable part of the lunar orbit.